The present invention relates to pad printers. More particularly, the present invention relates to a pad printer having a precise print locating system for use in single or multiple station printing systems.
Pad printing systems are used to apply high quality print, e.g. indicia. Pad printing systems use a deformable pad which receives ink, transferred as an image, from a cliché plate. The cliché has an etching or engraving of the indicia formed therein. The image is transferred from the pad to the item onto which the indicia is applied. Typically, the pad moves in a reciprocating motion to contact the cliché plate and then move away from the cliché plate to an indicia application position.
In typical pad printers that use a flat cliché plate, the cliché plate has the image to be printed etched into the plate. Ink is applied to (and excess wiped from) the cliché by an ink cup. The ink cup and cliché move relative to one another to apply ink to the cliché. After the ink cup and cliché move away from one another, the pad is brought into contact with the inked cliché to pick up the ink (ink is transferred to the pad). The pad is then brought into contact with the item to transfer the print onto the item.
In current pad printing systems, the inked cliché plate is precision located on the printing machine and the pad is moved precisely to the printing position. The image is transferred (or deposited) onto a precision located substrate. This system is also used in a multi-color applications in which the substrate may then be transferred, and precision located at the next color station for the same process.
In order to achieve the desired print accuracy and quality, the printer must be manufactured with accurate cliché locating characteristics, the cliché must be manufactured with an accurately located etched image, the printer must be manufactured with precise and accurate pad location on the inking stroke and on the printing stroke and the substrate conveyance and fixturing system must be manufactured with precise and accurate part location at each printing station.
While this system design has been widely accepted in pad printing over the years, it has been found to have limitations. For example, achieving the desired precision in pad and substrate motion or fixturing tend to increase the cost to design, manufacture and maintain the system. At the same time, the very features that enable such precision are items that are subject to wear and that must be regularly serviced, if the original precision level is to be maintained.
Accordingly, there is a need for a pad printing system that provides greater accuracy in the pad printing process. Desirably, such a system provides this increased accuracy, without the need for high maintenance equipment and components.